1. Field of the Invention
The invention relates to immunological reagents for therapeutic use, for example, in radioimmunotherapy (RAIT) and chemoimmunotherapy, and detection and/or diagnostic uses, for example, in radioimmunodetection (RAID), ultrasonography, and magnetic resonance imaging (MRI). In particular, the invention relates to naked antibodies (unconjugated) and directly-conjugated antibodies, as well as bi-specific antibodies (bsAbs) and bi-specific antibody fragments (bsFabs) which have at least one arm which is reactive against a targeted tissue and at least one other arm which is reactive against a linker moiety. Further, the invention relates to monoclonal antibodies that have been raised against specific immunogens, being human, humanized and chimeric monoclonal antibodies, as well as human, humanized and chimeric bi-specific antibodies and antibody fragments having at least one arm which is reactive against a targeted tissue and at least one other arm which is reactive against a linker moiety, DNAs that encode such antibodies and antibody fragments, and vectors for expressing the DNAs.
The present invention also relates to humanized, chimeric and human anti-CSAp antibodies, particularly monoclonal antibodies (mAbs), therapeutic and detection/diagnostic conjugates of humanized, chimeric and human anti-CSAp antibodies and methods of diagnosing/detecting or treating a malignancy using humanized, chimeric and human anti-CSAp antibodies. The present invention also relates to antibody fusion proteins or fragments thereof comprising at least two anti-CSAp mAbs or fragments thereof or at least one anti-CSAp mAb or fragment thereof and at least one second mAb or fragment thereof, other than the anti-CSAp mAb or fragment thereof. The humanized, chimeric and human anti-CSAp mAbs, fragments thereof, antibody fusion proteins thereof, or fragments thereof may be administered alone, as a therapeutic conjugate or in combination with a therapeutic immunoconjugate, with other naked antibodies, or with other therapeutic agents or as a diagnostic/detection conjugate. The present invention also provides DNA sequences encoding humanized, chimeric and human anti-CSAp antibodies, and antibody fusion proteins, vectors and host cells containing the DNA sequences, and methods of making the humanized, chimeric and human anti-CSAp antibodies.
2. Related Art
An approach to cancer therapy and detection/diagnosis involves directing antibodies or antibody fragments to disease tissues, wherein the antibody or antibody fragment can target a detection/diagnostic agent or therapeutic agent to the disease site. One approach to this methodology that has been under investigation involves the use of bi-specific monoclonal antibodies (bsAbs) having at least one arm that is reactive against a targeted diseased tissue and at least one other arm that is reactive against a low molecular weight hapten. In this methodology, a bsAb is administered and allowed to localize to target, and to clear normal tissue. Some time later, a radiolabeled low molecular weight hapten is given, which being recognized by the second specificity of the bsAb, also localizes to the original target. The same technology can be used to target therapeutic isotopes, drugs and toxins selectively to diseased tissues, particularly cancers against which the bsAb is targeted, or non-radioactive diagnostic agents for improved diagnosis and detection of pathological lesions expressing the target antigen.
Although low MW haptens used in combination with bsAbs possess a large number of specific imaging and therapy uses, it is impractical to prepare individual bsAbs for each possible application. Further, the application of a bsAb/low MW hapten system has to contend with several other issues. First, the arm of the bsAb that binds to the low MW hapten must bind with high affinity, since a low MW hapten is designed to clear the living system rapidly, when not bound by bsAb. Second, the non-bsAb-bound low MW hapten actually needs to clear the living system rapidly to avoid non-target tissue uptake and retention. Third, the detection and/or therapy agent must remain associated with the low MW hapten throughout its application within the bsAb protocol employed.
Of interest with this approach are bsAbs that direct chelators and metal chelate complexes to cancers using Abs of appropriate dual specificity. The chelators and metal chelate complexes used are often radioactive, using radionuclides such as cobalt-57 (Goodwin et al., U.S. Pat. No. 4,863,713), indium-111 (Barbet et al., U.S. Pat. No. 5,256,395 and U.S. Pat. No. 5,274,076, Goodwin et al., J. Nucl. Med. 33:1366-1372 (1992), and Kranenborg et al. Cancer Res (suppl.) 55:5864s-5867s (1995) and Cancer (suppl.) 80:2390-2397 (1997)) and gallium-68 (Boden et al., Bioconjugate Chem. 6:373-379, (1995) and Schuhmacher et al. Cancer Res. 55:115-123 (1995)) for radioimmuno-imaging. Because the Abs were raised against the chelators and metal chelate complexes, they have remarkable specificity for the complex against which they were originally raised. Indeed, the bsAbs of Boden et al. have specificity for single enantiomers of enantiomeric mixtures of chelators and metal-chelate complexes. This great specificity has proven to be a disadvantage in one respect, in that other nuclides such as yttrium-90 and bismuth-213, useful for radioimmunotherapy (RAIT), and gadolinium, useful for MRI, cannot be readily substituted into available reagents for alternative uses. As a result, iodine-131, a non-metal, has been adopted for RAIT purposes by using an I-131-labeled indium-metal-chelate complex in the second targeting step. A second disadvantage to this methodology requires that antibodies be raised against every agent desired for diagnostic or therapeutic use.
Thus, there is a continuing need for an immunological agent which can be directed to diseased tissue and is reactive with a subsequently administered linker moiety which is bonded to or associated with a therapeutic or diagnostic/detection metal chelate complex or a therapeutic or diagnostic/detection chelator.
The present invention relates to recombinantly produced chimeric, humanized and human monoclonal antibodies directed against cancers, including colorectal, pancreatic, and ovarian cancers. Chimeric, humanized and human monoclonal antibodies cause less production of human anti-mouse antibodies than completely murine antibodies. Additionally, when the antibodies are covalently conjugated to a diagnostic or therapeutic reagent, they retain their binding characteristics. Further, if the human, humanized or chimeric antibodies have human constant regions that can be immunologically functional in patients, such as is the case for IgG1, then these can also be active against such tumors as naked, or unconjugated, antibodies, and as such may also potentiate the antitumor effects of other therapeutic modalities, such as chemotherapy and radiation.
Colorectal, pancreatic, and ovarian cancers remain important contributors to cancer mortality. Their response to traditional chemotherapy and radiation therapy is mixed, however. Furthermore, these conventional forms of therapy have toxic side effects that limit their utility.
The use of monoclonal antibodies offers an alternative to traditional chemotherapy and radiation therapy. Tumor-specific and tumor-associated monoclonal antibodies can function alone (naked antibody therapy) or as conjugates in treatment regimens. The use of targeting monoclonal antibodies conjugated to radionuclides or other cytotoxic agents offers the possibility of delivering such agents directly to the tumor site, thereby limiting the exposure of normal tissues to toxic agents (Goldenberg, Semin. Nucl. Med., 19: 332 (1989); Goldenberg, D M, Radioimmunotherapy, in: Nuclear Medicine Annual 2001, L. Freeman, ed., Lippincott, William & Wilkins, Philadelphia, 2001, pp. 167-206). In recent years, the potential of antibody-based therapy and its accuracy in the localization of tumor-associated antigens have been demonstrated both in the laboratory and clinical studies (see, e.g., Thorpe, TIBTECH, 11: 42 (1993); Goldenberg, Scientific American, Science & Medicine, 1: 64 (1994); Baldwin et al., U.S. Pat. Nos. 4,923,922 and 4,916,213; Young, U.S. Pat. No. 4,918,163; U.S. Pat. No. 5,204,095; Irie et al., U.S. Pat. No. 5,196,337; Hellstrom et al., U.S. Pat. Nos. 5,134,075 and 5,171,665, Thorpe et al., U.S. Pat. No. 6,342,221, and Epstein et al., U.S. Pat. Nos. 5,965,132, 6,004,554, 6,071,491, 6,017,514, 5,882,626 and 5,019,368. In general, the use of radiolabeled antibodies or antibody fragments against tumor-associated markers for localization of tumors has been more successful than for therapy, in part because antibody uptake by the tumor is generally low, ranging from only 0.01% to 0.001% of the total dose injected (Vaughan et al., Brit. J. Radiol., 60: 567 (1987)). Increasing the concentration of the radiolabel to increase the dosage to the tumor is generally counterproductive, as this also increases exposure of healthy tissue to radioactivity.
Mu-9 is a murine monoclonal antibody of the IgG1 subtype, directed against the colon-specific antigen-p mucin (CSAp). CSAp is a tumor-associated antigen that is present in a high percentage of colorectal, as well as pancreatic and ovarian cancers. (Gold et al., Cancer Res., 50: 6405 (1990), and references cited therein). In pre-clinical and clinical testing, the antibody has shown excellent tumor targeting ability (Blumenthal et al., Int. J. Cancer, 22: 292 (1989); Sharkey et al., Cancer, 73(suppl): 864 (1994)). Mu-9 has an advantage over other antibodies that target tumor antigens because it recognizes an epitope, which is not present in the circulation (Pant et al., Cancer, 50: 919 (1982)). Circulating antigen can alter the delivery of antibody therapy because the antibody forms circulating immune complexes, which in turn could affect tumor targeting and antibody pharmacokinetics and biodistribution.
As with most other promising non-human antibodies, the clinical use of murine Mu-9 may be limited by the development in humans of anti-mouse antibody (HAMA) responses. This can limit the diagnostic/detection and therapeutic usefulness of the antibodies, not only because of the potential anaphylactic problem, but also because a major portion of the circulating antibody may be complexed to and sequestered by the circulating anti-mouse antibodies. The production of HAMA may also affect the accuracy of murine antibody-based immunoassays. Thus, HAMA responses in general pose a potential obstacle to realizing the full diagnostic and therapeutic potential of the Mu-9 antibody.
In order to maximize the value of the Mu-9 antibody as a therapeutic or diagnostic/detection modality and to increase its utility in multiple and continuous administration modalities and settings, an object of this invention is to provide a mouse-human chimeric mAb (cMu-9), a fully human, and a humanized mAb (hMu-9) that relate to Mu-9 by retaining the antigen-binding specificity of Mu-9, but that elicit reduced HAMA or other immune responses in a subject receiving the same.
Another object of this invention is to provide DNA sequences that encode the amino acid sequences of the variable regions of the light and heavy chains of the cMu-9, human Mu-9, and hMu-9 mAbs, including the complementarity-determining regions (CDRs).
A further object of this invention is to provide conjugates of the hMu-9, human Mu-9, and cMu-9 mAbs containing therapeutic or diagnostic/detection modalities.
Another object of this invention is to provide combinations of antibodies with CSAp antibody or antibodies with other carcinoma-targeting antibodies, wherein said antibodies can be used as naked immunoglobulins or as conjugates with drugs, toxins, isotopes, cytokines, enzymes, enzyme-inhibitors, hormones, hormone antagonists, and other therapy-enhancing moieties.
Yet another object of this invention is to provide methods of therapy and diagnosis/detection that utilize the humanized, chimeric and fully human MAbs of the invention.